The present invention relates to the use of materials for protecting crops from pathogenic attack.
In particular, the present invention relates to the use of fish oils and novel compositions containing the fish oils, which upon application to a crop, protect the crop against fungal infections. The prior art teaches a wide variety of materials which protect plants and enhance their growth. For example, U.S. Pat. No. 3,712,803, discloses the use of an aqueous mixture of proteinaceous material and an alkaline metal ligonsulfonate subjected to the acid hydrolysis and then oxidation, which when applied to plants and trees as a spray, or as an addition to the root zone soil, imparts freeze resistance to the plants and trees.
U.S. Pat. No. 2,013,063, discloses the use of spraying a plant with an aqueous wax emulsion, containing a colloidal earth, an ammonium salt of a drying acid, i.e., unsaturated fatty acids such as those derived from soya, fish or beans, whereby a permeable antidessicant film is formed.
U.S. Pat. No. 2,198,991, discloses a method for protecting living trees and plants from sunscald, borer and fungus injury by treating the trunks and branches with an aqueous emulsion comprising a paraffin wax, an ammonium salt of a drying acid, as defined in U.S. Pat. No. 2,013,063, a colloidal earth and finely divided aluminum.
There is also prior art that teaches the use of various oils, including fish oils, as a useful physical component to optimize stability of a plant protecting suspension of an active ingredient. For example, U.S. Pat. Nos. 4,826,863 and 4,734,432, disclose the use of various oils, including paraffin, soya, fish and mineral oils, together with, inter alia, the active ingredient such as a fungicide or herbicide, to provide a stabilized plant protecting agent suspension.
U.S. Pat. No. 4,761,423 discloses the use of a vegetable, animal or mineral oil together with, inter alia, a fungicide or insecticide to form an improved seed dressing.
U.S. Pat. Nos. 3,728,454, 3,725,557 and 3,728,453 disclose the use of pine or fish oil, together with, inter alia, the active ingredient, alloxan or alloxantin, or dialuric acid, respectively, to inhibit the growth of herbs bacteria, fungi and other microorganisms.
There is a serious limitation to the above teachings, in that non-natural products are used to provide plants protection against fungal diseases.
The literature has recently reported that some unsaturated fatty acids, which are natural products, applied externally to the lower leaves of potato plants protected the upper leaves against a challenge infection of the late blight fungus Phytophthora infestans (see Cohen et al., "Systemic Resistance of Potato Plants Against Phytophthora infestans Induced by Unsaturated Fatty Acids", Physiol. and Molecular Plant Pathol. 38:255-263, 1991). However, there is a serious drawback to the use of the said unsaturated fatty acids, even when used with low application rates, those that were significantly effective in providing protection were phytotoxic to the potato leaves.
For these and other reason, there is thus a widely recognized need for effective natural products that can lie sprayed on plants to protect them against fungal diseases, that induce no phytotoxicity.